Question: $ { {3} \times \left[\begin{array}{rr}{3} & {1} \\ {0} & {-2} \\ {4} & {0}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{3}\times{3} & {3}\times{1} \\ {3}\times{0} & {3}\times{-2} \\ {3}\times{4} & {3}\times{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{9} & {3} \\ {0} & {-6} \\ {12} & {0}\end{array}\right]}$